Due to rapid changes in the patterns of daily life and industrial activity and the material consumption related thereto, the volume of waste material generated by the public and by industry is increasing year by year. Several ways have been proposed for disposing of such waste matter by way of land reclamation and burning, etc. However, depending on the nature of the waste matter in question, the procedures heretofore applied are not totally suitable because of the possibility of pollution with respect to certain materials involved.
For instance, the waste matter discharged from nuclear power plants has been stored in tanks provided within the plants because of concern regarding environmental pollution. Such waste matters include spent ion exchange resins (granule or powder), spent filtering materials, spent active carbon, filters (cellulose, synthetic) and precoating material, etc. However, the volume of such waste matter being stored is increasing, and thus, it has been desired that an effective way of disposing of such waste matter be developed. To such end, it has been proposed that microwave energy be utilized in order to directly irradiate the waste matter with microwaves so as to heat and incinerate the waste matter. For example, one of such proposals is disclosed in Japanese patent application No. 109521/84.
However, if such an incinerator as above using microwave energy is employed to incinerate the waste matter referred to above, the following drawbacks are observed. That is:
(1) waste matter tends to be initially dried upon being subjected to microwave energy and this dried matter is poor in absorption of microwave energy;
(2) it is difficult to expect satisfactory incineration in a case where high molecular plastic such as ion exchange resin is subjected to incineration because a large volume of tar and unburnt carbon will be generated unless the atmospheric conditions are suitable for supplying sufficient oxygen at high temperatures;
(3) without maintaining uniform distribution of the waste matter all over the hearth and uniform radiation of microwaves on the waste matter, it would be difficult to achieve satisfactory incineration due to localized burning which may result in localized over-heating;
(4) smooth incineration would be difficult when incinerating particularly high molecule plastics since such plastics exhibit a tendency to produce an aggregated mass by melting and thus, the inside of such mass may not contact air and may merely be carbonized.
Further, a large amount of hazard gas, tar and soot, etc. would be produced within the incinerator and it would be difficult to dispose of such matter within the same incinerator unless the capacity of the incinerator were made larger than that required for the incineration and the temperature were kept relatively high;
(5) processing is restricted to a batch system and, thus, an effective continuous operation is not possible and the composition of the discharged gas may not be kept constant; and
(6) construction of the incinerator is complex due to the fact that the agitator is arranged in the upper part where the microwaves are introduced, and discharge duct or waste supply are arranged and, further, air is sometimes supplied into the incinerator through the blades of the agitator.